屏幕截图--Take-ScreenShot分析

C#代码分析

$code = @' 
using System; 
using System.Runtime.InteropServices; 
using System.Drawing; 
using System.Drawing.Imaging; 
namespace ScreenShotDemo 
{ /// <summary> /// Provides functions to capture the entire screen, or a particular window, and save it to a file. /// </summary> public class ScreenCapture { /// <summary> /// Creates an Image object containing a screen shot the active window /// </summary> /// <returns></returns> public Image CaptureActiveWindow() { #GetForegroundWindow获取一个前台窗口的句柄（用户当前工作的窗口）#[DllImport("user32.dll")]#private static extern IntPtr GetForegroundWindow();return CaptureWindow( User32.GetForegroundWindow() ); } /// <summary> /// Creates an Image object containing a screen shot of the entire desktop /// </summary> /// <returns></returns> public Image CaptureScreen() { #GetDesktopWindow，该函数返回桌面窗口的句柄。桌面窗口覆盖整个屏幕。桌面窗口是一个要在其上绘制所有的图标和其他窗口的区域。return CaptureWindow( User32.GetDesktopWindow() ); }     /// <summary> /// Creates an Image object containing a screen shot of a specific window /// </summary> /// <param name="handle">The handle to the window. (In windows forms, this is obtained by the Handle property)</param> /// <returns></returns> private Image CaptureWindow(IntPtr handle) { // get te hDC of the target window #GetWindowDC函数：返回hWnd参数所指定的窗口的设备环境IntPtr hdcSrc = User32.GetWindowDC(handle); // get the size User32.RECT windowRect = new User32.RECT(); //GetWindowRect是一个Windows API函数。该函数返回指定窗口的边框矩形的尺寸，函数原型为void GetWindowRect(LPRECT lpRect) constUser32.GetWindowRect(handle,ref windowRect); //获取宽度和高度int width = windowRect.right - windowRect.left; int height = windowRect.bottom - windowRect.top; // create a device context we can copy to #该函数创建一个与指定设备兼容的内存设备上下文环境（DC）IntPtr hdcDest = GDI32.CreateCompatibleDC(hdcSrc); // create a bitmap we can copy it to, // using GetDeviceCaps to get the width/height //CreateCompatibleBitmap该函数用于创建与指定的设备环境相关的设备兼容的位图IntPtr hBitmap = GDI32.CreateCompatibleBitmap(hdcSrc,width,height); // select the bitmap object //函数功能：该函数选择一对象到指定的设备上下文环境中，该新对象替换先前的相同类型的对象。IntPtr hOld = GDI32.SelectObject(hdcDest,hBitmap); // bitblt over //bitblt就实现了将位图从新创建的设备环境中copy到当前的设备环境当中//BitBlt 用于从原设备中复制位图到目标设备//BitBlt(int x,int y,int nWidth,int nHeight,CDC*pSrcDC,int xSrc,int ySrc,DWORDdwRop);//参数：//x：目标矩形区域的左上角x轴坐标点。//y：目标矩形区域的左上角y轴坐标点。//nWidth：在目标设备中绘制位图的宽度。//nHight：在目标设备中绘制位图的高度。//pSrcDC：源设备上下文对象指针。//xSrc：源设备上下文的起点x轴坐标，函数从该起点复制位图到目标设备。//ySrc：源设备上下文的起点y轴坐标，函数从该起点复制位图到目标设备。//dwRop：光栅操作代码//BLACKNESS           使用黑色填充目标区域//DSTINVERT              目标矩阵区域颜色取反//MERGECOPY            使用与运算组合原设备矩形区域的颜色和目标设备的画刷//MERGEPAINT           使用或运算将反向的源矩形区域的颜色和目标矩形区域的颜色合并//NOTSRCCOPY          复制源设备区域的反色到目标设备中//NOTSRCERASE        使用或运算组合源设备区域与目标设备区域的颜色，然后对结果颜色取反//PATCOPY                  复制源设备当前选中的画刷到目标设备//PATINVERT               使用异或运算组合目标设备选中的画刷和目标设备区域的颜色//PATPAINT                 通过或运算组合目标区域当前选中的画刷和源设备区域反转的颜色//SRCAND                   使用与运算组合源设备和目标设备区域的颜色//SRCCOPY                 直接复制源设备区域到目标设备中//SRCERASE               使用与运算组合目标设备区域的反色与源设备区域的颜色//SRCINVERT              使用异或运算组合源设备区域颜色和目标设备区域颜色//SRCPAINT                 使用或运算组合源设备区域颜色和目标设备区域颜色//WHITENESS             使用白色填充目标区域//GDI32.BitBlt(hdcDest,0,0,width,height,hdcSrc,0,0,GDI32.SRCCOPY); // restore selection GDI32.SelectObject(hdcDest,hOld); // clean up //该函数删除指定的设备上下文环境（Dc）GDI32.DeleteDC(hdcDest); //ReleaseDC函数释放设备上下文环境（DC）供其他应用程序使用User32.ReleaseDC(handle,hdcSrc); // get a .NET image object for it //从 Windows 句柄创建 Bitmap Image img = Image.FromHbitmap(hBitmap); // free up the Bitmap object GDI32.DeleteObject(hBitmap); return img; } /// <summary> /// Captures a screen shot of the active window, and saves it to a file /// </summary> /// <param name="filename"></param> /// <param name="format"></param> public void CaptureActiveWindowToFile(string filename, ImageFormat format) { Image img = CaptureActiveWindow(); //将此 Image 以指定格式保存到指定文件img.Save(filename,format); } /// <summary> /// Captures a screen shot of the entire desktop, and saves it to a file /// </summary> /// <param name="filename"></param> /// <param name="format"></param> public void CaptureScreenToFile(string filename, ImageFormat format) { Image img = CaptureScreen(); img.Save(filename,format); }     /// <summary> /// Helper class containing Gdi32 API functions /// </summary> private class GDI32 { public const int SRCCOPY = 0x00CC0020; // BitBlt dwRop parameter [DllImport("gdi32.dll")] public static extern bool BitBlt(IntPtr hObject,int nXDest,int nYDest, int nWidth,int nHeight,IntPtr hObjectSource, int nXSrc,int nYSrc,int dwRop); [DllImport("gdi32.dll")] public static extern IntPtr CreateCompatibleBitmap(IntPtr hDC,int nWidth, int nHeight); [DllImport("gdi32.dll")] public static extern IntPtr CreateCompatibleDC(IntPtr hDC); [DllImport("gdi32.dll")] public static extern bool DeleteDC(IntPtr hDC); [DllImport("gdi32.dll")] public static extern bool DeleteObject(IntPtr hObject); [DllImport("gdi32.dll")] public static extern IntPtr SelectObject(IntPtr hDC,IntPtr hObject); } /// <summary> /// Helper class containing User32 API functions /// </summary> private class User32 { [StructLayout(LayoutKind.Sequential)] public struct RECT { public int left; public int top; public int right; public int bottom; } [DllImport("user32.dll")] public static extern IntPtr GetDesktopWindow(); [DllImport("user32.dll")] public static extern IntPtr GetWindowDC(IntPtr hWnd); [DllImport("user32.dll")] public static extern IntPtr ReleaseDC(IntPtr hWnd,IntPtr hDC); [DllImport("user32.dll")] public static extern IntPtr GetWindowRect(IntPtr hWnd,ref RECT rect); [DllImport("user32.dll")] public static extern IntPtr GetForegroundWindow();       } } 
} 
'@ 

下面的powershell代码

#User Add-Type to import the code 
#通过代码添加新类型
#ReferencedAssemblies指定类型所依赖的程序集。默认情况下，Add-Type 引用 System.dll 和System.Management.Automation.dll
add-type $code -ReferencedAssemblies 'System.Windows.Forms','System.Drawing' 
#Create the object for the Function 
$capture = New-Object ScreenShotDemo.ScreenCapture #Take screenshot of the entire screen 
If ($Screen) { Write-Verbose "Taking screenshot of entire desktop" #Save to a file If ($file) { If ($file -eq "") { $file = "$pwd\image.bmp" } Write-Verbose "Creating screen file: $file with imagetype of $imagetype" $capture.CaptureScreenToFile($file,$imagetype) } ElseIf ($print) { $img = $Capture.CaptureScreen() #从 Windows 窗体应用程序打印时，定义一种可重用的可发送到打印机上的对象 $pd = New-Object System.Drawing.Printing.PrintDocument #在指定位置以原始大小绘制指定的Image。#Graphics.DrawImage#使用其原始物理尺寸在坐标对指定的位置绘制指定的图像#public void DrawImage (System.Drawing.Image image, int x, int y);$pd.Add_PrintPage({$_.Graphics.DrawImage(([System.Drawing.Image]$img), 0, 0)}) $pd.Print() }         Else { $capture.CaptureScreen() } } 
#Take screenshot of the active window     
If ($ActiveWindow) { Write-Verbose "Taking screenshot of the active window" #Save to a file If ($file) { If ($file -eq "") { $file = "$pwd\image.bmp" } Write-Verbose "Creating activewindow file: $file with imagetype of $imagetype" $capture.CaptureActiveWindowToFile($file,$imagetype) } ElseIf ($print) { $img = $Capture.CaptureActiveWindow() $pd = New-Object System.Drawing.Printing.PrintDocument $pd.Add_PrintPage({$_.Graphics.DrawImage(([System.Drawing.Image]$img), 0, 0)}) $pd.Print() }         Else { $capture.CaptureActiveWindow() }     }      
}